Abstract: The effects of aging treatment after pre-twinning on the precipitation and bending deformation behavior at room temperature of AZ80 magnesium alloy were studied by optical microscope(OM) and scanning electron microscope(SEM). The results show that aging at 180 ℃for 0.5 h can significantly promote the precipitation at grain boundary, and the addition of twins boundary can also promote the precipitation. When the precompressed-samples are stretch in reverse after pre-twining, the number of twins in AZ80 magnesium alloy structure is decreased because of detwinning. The tensile yield strength is reduced due to detwinning. After bending the pre-twinning specimen at 100 ℃, the tensile debonding behavior occurs on the outside of the bending specimen. Due to the compression load, the number of twins in the inner structure increases, while the number of twins in the middle changes from variable to less. The increase of the second phase particles inhibits the generation of detwinning behavior.